Surface properties of Ti6Al4V using TiCN/DLC coatings deposited by plasma-assisted chemical vapor deposition

In this study, diamond-like carbon (DLC) and titanium carbonitride (TiCN) coatings were deposited as gradient interlayers on a Ti-6Al-4V (Ti64) utilizing the PACVD method to improve its surface properties. TiCN is required to enhance hardness, reduction elastic modulus (Er), and interface bonding. results showed that increasing the deposition time of the TiCN interlayer from 2 to 3 h improved the adhesion of the DLC and increased the thickness to 1009.40 nm. To investigate the mechanical and tribological properties, nanoindentation, hardness testing, adhesion, and pin-on-disk (POD) tests were used. FESEM, OM, XRD, and Raman spectroscopy were utilized to investigate the surface of samples. The Ti64 substrate coating has a lower indentation depth (192 nm), hardness (3.8-4.7 GPa), and greater dispersion of the Er with a range of 136-171 GPa. Ti64-TiCN/DLC exhibits oscillations in the coefficient of friction (µ) that are both upward and downward. The uncoated substrate has a µ in the approximately constant range of 0.23. The experiment found that uncoated samples have a higher average wear rate (7.8×10-13 m3/N.m). OM images showed that the wear mechanism of the Ti64-TiCN/DLC is the adhesive type, while the uncoated substrate is abrasive.